[From: Scripture, Tradition, and Rome, Part 2 by John MacArthur]: "...[I]t is not hard to understand why in recent years Catholic apologists have attacked sola Scriptura with a vengeance. If they can topple this one doctrine, all the Reformers' other points fall with it. For under the Catholic system, whatever the Church says must be the standard by which to interpret all Scripture. Tradition is the "true" Scripture, written in the heart of the Church. The Church--not Scripture written in "documents and records"--defines the truth about justification by faith, veneration of saints, transubstantiation, and a host of other issues that divided the Reformers from Rome.

To put it another way, if we accept the voice of the Church as infallibly correct, then what Scripture says about these questions is ultimately irrelevant. And in practice this is precisely what happens. To cite but one example, Scripture very plainly says, "There is one God, and one mediator also between God and men, the man Christ Jesus" (1 Tim. 2:5). Nonetheless, the Catholic Church insists that Mary is her Son's "co-mediatrix." And in the eyes of millions of Catholics, what the Church says is seen as the final and authoritative Word of God.
First Timothy 2:5 is thus nullified by Church tradition.

If Rome can prove her case against sola Scriptura, she overturns all the arguments for the Reformation in one fell swoop. If she can establish her tradition as an infallible authority, no mere biblical argument would have any effect against the dictates of the Church..."
Scripture, Tradition, and Rome, Part 2 by John MacArthur

Catholics have a different Jesus, a different
gospel and a different way of salvation.
Understand what scripture teaches.